Centrifugal distortion analysis for the bent isomer of N 2OHF

Abstract

Six previously unobserved lines for the bent form of NNO-HF (O…H hydrogen bonded) were measured using a pulsed-beam, Fourier-transform spectrometer. These lines, together with earlier data, were fitted to obtain the rotational constants and a limited set of quartic distortion constants using a Watson-type Hamiltonian in the I r representation. The results of the fit are: A+Δ K =26322.32(32) MHz, B=2720.93(10) MHz, C=2438.72 (10) MHz, Δ J =60.3(11) kHz, Δ JK =−3.077(15) MHz, δ J = 13.1(10) kHz and δ K = 314 (47) kHz. The errors in line frequencies calculated with this extended set of parameters are two orders of magnitude smaller than errors obtained using only rigid rotor parameters. The vibrationally averaged structure and force constants for the R c.m. stretching vibration and an in-plane-bending vibration were calculated using the rotational constants and distortion constants. It was found that Δ J (or D J ) depends primarily on f RR −1, so that earlier analyses involvi Δ J or D J were reasonably accurate.